This is a tricky one…
I found out that some of mine Virtual Machines in different host machines were getting the same MAC Address.
With some research I found out the problem was using the same image (WIM) for deployment, that has already Hyper-V role installed.
After a little googling I’ve noticed that this is a problem that a lot of people are complaining.
So…there are to approaches to take here:
Creating new images
When creating new images for deployment, just delete the following keys before sysprep the machine:
Already Installed Machines
For this one, run the vbscript published at TechNet Forums:
Script to reset VM MAC Addresses
After running the script don’t forget to restart the virtual machines.
Hope this helps some people like it really helped me!